Alpine SWR-823D / 843D 8" Subwoofers - Page 40 - Car Audio | DiyMobileAudio.com | Car Stereo Forum

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Old 09-22-2015   #976
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Default Re: Alpine SWR-823D / 843D 8" Subwoofers

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Originally Posted by ninetysix View Post
The alpine manual says 175mm and from memory that sounds about right. So that might be a bit tight, although with a baffle on it you might just make it?

Are you sure Jim said .01 and not 0.1? I seem to remember the demo Car he had them in were 0.1, and I'm running about .23 I think. I can't really comment on how they would work in much smaller boxes.

As for sound, they are great! I've only has minimal time for Tuning in the 4 weeks I've had off work but they are working out well. Only trouble I'm having is integrating the 12" sub and having it actually contribute much to the sound.

I've had best results so far with the minidsp crossing the 8s and the components at somewhere around 200-250hz 24dB Linkwitz-Riley and they play very happily down to 50hz. With the 12" out of the Car they seem to be almost good enough with no hpf at all. Almost.

They definitely needed a lot more than 150w a side, really came alive with 350w and sweeter still with 450w. Both sides had a nasty peak at about 90hz (left about 6dB and the right about 8dB) but easy to correct. Imaging is quite good too, tho I had to get the components a little more on axis to forget the 8s were on the floor.


Cheers
Yes .1 my bad. I wonder if I can do them under the seats as well in my durango and then run a 2 way in the factory door locations. Say a 5.25 and tweeter. Hmmm
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Old 09-22-2015   #977
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Default Re: Alpine SWR-823D / 843D 8" Subwoofers

I doubt there's a Car you can't put 8s on the floor of. But when your holding a knife to the carpet, you've gotta ask yourself one question... "Do I feel lucky?"

You've gotta have a DSP and a few weeks off work to get it working tho (and I ain't there yet). So far the Mrs Subaru with hertz mille mlk165.3 6.5" components and an old MB quart sub is proving very difficult to compete with. Running passive with lots of power. Xover and TA from head unit and it's awesome. Makes me sick.

5.25 would probably match nicely, my 6" Boston SPZs seem a little out of their efficiency range only running down to 200hz
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Old 09-22-2015   #978
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Default Re: Alpine SWR-823D / 843D 8" Subwoofers

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Originally Posted by ninetysix View Post
I doubt there's a Car you can't put 8s on the floor of. But when your holding a knife to the carpet, you've gotta ask yourself one question... "Do I feel lucky?"

You've gotta have a DSP and a few weeks off work to get it working tho (and I ain't there yet). So far the Mrs Subaru with hertz mille mlk165.3 6.5" components and an old MB quart sub is proving very difficult to compete with. Running passive with lots of power. Xover and TA from head unit and it's awesome. Makes me sick.

5.25 would probably match nicely, my 6" Boston SPZs seem a little out of their efficiency range only running down to 200hz
I have a dodge durango, its a suv. And i will be using a rockford fosgate 360.3 to handle eq and t/a. the under the seat location allows me to grab a nice set of 5.25 driver with more emphasis on a set that can play the mid-range and highs better with little regards to how much mid-bass a set would provide.

OK just checked..yeah not gonna happen with my vehicle. so back to the door install.

Last edited by manish; 09-22-2015 at 10:21 AM..
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Old 10-08-2015   #979
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Default Re: Alpine SWR-823D / 843D 8" Subwoofers

quick update...

my plan of using these for midbass drivers has kind of backfired, as it turns out they are awesome as front subs. After improving the install of my SPZ60s (the painted MDF spacers had turned to mush) I've got good strong midbass. I've currently got them crossed high & low at 80hz 24dB LR

I've taken the 12" out of the trunk as I just wasn't happy with it.

Seeing as these 8s are now my subs I've made the boxes a little bigger, from .21 up to about .3

Heres a chart from REW, blue line .21 and green .3

Attached Images
File Type: jpg .21 vs .3 swr843d.jpg (24.5 KB, 113 views)

Last edited by ninetysix; 10-08-2015 at 07:29 PM.. Reason: wrong chart
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Old 02-04-2016   #980
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Default Re: Alpine SWR-823D / 843D 8" Subwoofers

Me again with some quite possibly useless info.

So I went back to using my SWR-843Ds as midbass drivers and added a SWR-12D4 in the trunk, but instead of the rear firing ported box I previously had I went with a sealed box of about 0.9ft3 net firing through the ski-pass and sealed up against it with polystyrene. No more -20dB dip at 40Hz, and plays flat down to 10Hz, if you can hear that.

I've spent countless days and evenings endlessly tweaking the setup, the Mrs is pretty sick of it and I have to thaw my own frozen hotdogs in the sink at night when I come in.

I'm powering the two 8s up front from a pair of soundstream picasso nano 450w monoblocs, which unfortunately have a LPF you can't turn off that maxes out at 250Hz (BW-2 I believe). With the 0.25ft3 net sealed boxes I'm pushing the alpines way too hard to get good output above 120Hz or so, crossed 70-200ish the amps are burning hot after a tweak session... But run them as subs with 80 to 100hz LPF and they have good output and the amps don't get hot. I appreciate the fact that I probably bought the wrong amps for this application. But not much changed running them through my Boston GT-4100 4x100 amp that I use for my active comps which can do 2x450 bridged 2x2ohm. Both amps caused the woofers to make some nasty mechanical noises when pushed hard above 100Hz, making me think these just aren't the drivers for the task.

So I figured with nothing to lose, I'd try porting them with a fairly high tuning frequency which somebody here suggested to me a while back. Only did the one box so far, and I messed up with my calculations... I was gonna try 2x50mm PVC electrical conduit ports (~43mm ID, 1.7") which boxtunecalc on my phone said they would need to be 12" long. Then I thought I'll just try one 50mm port to see what the output is like regardless of port noise... But I forgot to switch to 1 port instead of 2, so one 12" port it was.

Playing test tones the woofer looked and felt like excursion was at its lowest around 38Hz, and the mic looks to agree with that with a nearfield measurement. Port noise down low is atrocious as expected, but by about 60Hz its pretty much inaudible. Really impressed at the high end boost considering the tuning frequency is almost half what I was planning!

Attached is a nearfield measurement from the sealed 8 that I haven't modified (and they both measured basically identically previously), nearfield from the newly ported 8 showing both woofer (blue) and port (red) measurements, a sweep with the sealed 8 and a sweep from the ported 8. All 5-500Hz, set the volume so all measurements came up at about -29 when clicking check levels in REW. Port measurement is as is, I haven't factored in the difference in diameter. The volume setting was basically the same for all measurements, although I turned the gain on the ported 8 amp down quite a bit. Sealed 8 had no XO set, the ported 8 had a 30Hz BW-4 high pass to limit over excursion. Mic was in the same spot for both sweeps, about 12" away from the rear vision mirror.


Not sure i'll change the port length straight away, but I found the results very interesting and I think it shows these 8s really are happier in a ported box, even if way too small. Still might be in the market for different drivers, but we'll see.

Cheers
Attached Images
File Type: jpg sealed 8 nearfield.jpg (25.8 KB, 20 views)
File Type: jpg ported 8 nearfield.jpg (30.0 KB, 18 views)
File Type: jpg sealed 8 sweep.jpg (27.6 KB, 22 views)
File Type: jpg ported 8 sweep.jpg (27.9 KB, 19 views)
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